WO2009082848A1 - A method for radio link control entity reset - Google Patents

Abstract

A method for radio link control entity reset is provided, it includes: a Timer_Discard timer is set respectively for each Packet Data Convergence Protocol Service Data Unit, and the corresponding Timer_Discard timer is started when an upper layer of the Packet Data Convergence Protocol forwards a Service Data Unit; in the case of the started Timer_Discard timer overtime, if the Service Data Unit corresponding to the started Timer_Discard timer has been forwarded to a Radio Link Control entity and has been assigned a Radio Link Control sequence number, then a Radio Link Control Timer_RST timer is started; in the case of the started Timer_RST timer overtime, if not all the Protocol Data Units related to the Service Data Unit are sent successfully, then the Radio Link Control reset procedure is started. The present invention can prevent from buffer overload and radio resource waste and unfairness caused by immediately discarding the Service Data Unit, and can simplify the processing mechanism, it can reduce the number of timers, and can lessen processing complexity and overhead.

Description

 TECHNICAL FIELD The present invention relates to the field of digital mobile communications, and in particular to a wireless link control

(Radio Link Control, RLC) The reset method of the entity. BACKGROUND OF THE INVENTION The radio link control layer of the Wideband Code Division Multiple Access (WCDMA) radio interface of the third generation mobile communication system includes three types of RLC entities: Transparent Mode (TM), non-confirmed Unacknowledged Mode (UM) and Acknowledged Mode (AM). The TM RLC entity and the UM RLC entity may be configured to send an RLC entity or receive an RLC entity, the sending RLC entity sends a Radio Link Control Protocol Data Unit (RCC PDU), and the receiving RLC entity receives the RLC PDU. The AM RLC entity includes a transmitting end and a receiving end, wherein the transmitting end AM RLC entity sends an RLC PDU, and the receiving end AM RLC entity receives the RLC PDU. The AM RLC entity provides a reliable data transmission service using the ARQ (Automatic Retransmission Request) mechanism. ,

The transmitters of the TM RLC entity, the UM RLC entity, and the AM RLC entity support a timer-based Radio Link Control Service Data Unit (RSC Discard Service) (SDU Discard), and the AM RLC entity also Supports SDU discarding based on the maximum number of RLC PDUs sent. In the timer-based SDU discarding function, the timer is set at the RLC layer. When the RLC layer receives an RLC SDU from the upper layer protocol layer, the timer Timer-Disard is started. The value of the timer is configured by the upper layer protocol layer. When the relevant RLC PDU cannot be successfully sent before the timer expires or after several times of retransmission, the relevant RLC PDU is discarded from the buffer of the RLC PDU to avoid buffer overload. TM RLC entities and UM RLC entities can be configured by the higher layer protocol layer to use SDU

The Discard function does not use the SDU Discard function. When the SDU Discard function is not configured on the UM RLC entity, the related RLC PDU can be discarded only when the transmit buffer is full. When the SDU Discard function is not configured on the TM RLC entity, it can be discarded when the sender receives a new SDU from the upper layer protocol layer.

1 P 17247 SDU received at the previous Transmission Timer Interval (TTI) When the TM RLC entity and the UM RLC entity are configured with the SDU Discard function, the timer-based discard (without explicit signaling) is used. Signalling) discards the "■ mechanism. The sender initiates a timer for each SDU received from the higher layer protocol layer to monitor the

The transmission time of the SDU, when the transmission time exceeds the configured value, the sender discards the SDU, and does not need to explicitly signal the TM RLC or UM RLC entity of the receiver. The AM RLC entity must be configured with the SDU Discard function and supports three SDU Discard mechanisms, which are: "Determination of Timer based discard (with explicit signalling)", "After exceeding the maximum number of transmissions" "SDU discard after MaxDAT number of transmissions", "No discard after MaxDAT number of transmissions", where "Timer-based discarding with explicit signaling" mechanism The basic principle is: The sender starts a timer Timer- Discard for each SDU received from the upper layer protocol layer, and when the timer expires, the sender discards the SDU. When the "send mobile reception window (Send MRW) is configured. "The function or the one or more fragments of the discarded SDU have been delivered to the underlying protocol layer, and the receiving end discards the corresponding RLC PDU by explicit signaling. The basic principle of the "discard after exceeding the maximum number of transmissions" mechanism is: When the number of times an AM RLC data PDU (AMD PDU) is scheduled to be sent reaches the maximum number of transmissions MaxDAT The transmitting side discards the associated SDU, and notifies the receiving end discards the corresponding RLC PDU by explicit signaling.

The basic principle of the mechanism of "Do not discard after exceeding the maximum number of transmissions" is: When the number of times an AMD PDU is scheduled to be sent reaches the maximum number of transmissions MaxDAT, the sender initiates an RLC Reset (RLC Reset) process.

The "Send Mobile Receive Window (Send MRW)" function is used by the AM RLC entity to discard the SDU and use explicit signaling to notify the receiving end to discard the corresponding AMD PDU to update the receive window. Figure 1 shows the basic principle of the "Send MRW" function. As shown in Figure 1, the sender sets the "Mobile Receive Window Super Field (MRW SUFI)" after discarding the relevant SDU, which contains the necessary information of the discarded SDU, and includes the MRW SUFI in the Status Protocol Data Unit Status PDU to notify the reception. End AM RLC entity, start timer Timer MRW.

2 P 17247 After receiving the Status PDU containing the MRW SUFI, the corresponding AMD PDU is discarded according to the information in the MRW SUFI and the other related AMD PDUs are delivered to the upper layer protocol layer. The mobile receiving window is confirmed to confirm the super field MRW_ACK SUFI direction. The sender AM RLC entity responds. After the sender AM RLC entity correctly receives the MRW_ACK SUFI, it updates the transmission window according to the information therein, stops the timer Timer_MRW, and completes the Send MRW process. If the Send MRW process is not completed when the timer Timer-MRW times out, in the case where the MRW SUFI transmission does not reach the maximum number of times MaxMRW, the sender resets the MRW SUFI to the receiving end; if the MRW SUFI transmission has reached the maximum number of times, the transmission is performed. Terminates the Send MRW process and initiates the RLC reset process. The RLC reset procedure is used to reset two peer AM RLC entities. As shown in Figure 2, during the RLC reset, the superframe number HFN used by the encryption function needs to be synchronized between the two AM RLC entities. When the RLC reset process is initiated, the sender stops sending all AMD PDUs or Status PDUs, ignores all received AMD PDUs or Status PDUs, sets the reset protocol data unit RESET PDUs to the underlying protocol layer, and starts the timer Timer_RST. After receiving the RESET PDU correctly, the receiving end submits a reset acknowledgment protocol data unit RESET ACK PDU to the underlying protocol layer, and performs RLC reset, including initializing related state variables, stopping related timers, resetting related configuration parameters, and discarding related RLC SDUs and RLC PDUs. Wait. After the sender receives the RESET ACK PDU correctly, it performs RLC reset, including initializing the relevant state variable, stopping the related timer, resetting the relevant configuration parameters, discarding the relevant RLC SDU and RLC PDU, etc., thereby completing the RLC reset process. If the RLC reset process is not completed when the timer Timer-RST expires, the sender resets the RESET PDU transmission if the transmission of the RESET PDU does not reach the maximum number of transmissions MaxRST. If the transmission of the RESET PDU reaches the maximum number of transmissions, an error that cannot be recovered is reported to the higher layer protocol layer. The third generation mobile communication long-term evolution (LTE: Long Term Evolution) system radio interface radio link control layer (RCC: Radio Link Control) also includes three types of RLC entities: TM RLC entity, UM RLC entity and AM RLC entity. The LTE radio interface also supports a timer-based SDU Discard function. The SDU discard timer is set in the Packet Data Convergence Protocol layer (PDCP), and the PDCP layer is a high-layer protocol layer located above the RLC layer. Each PDCP SDU sets a timer, which is started when the upper layer of the PDCP layer delivers the data packet. When the timer expires, the PDCP SDU that has not been submitted to the RLC layer can be discarded and/or has been submitted to the RLC layer but still at the RLC layer. The PDCP SDU without the RLC sequence number is allocated. For the PDCP SDU that has been submitted to the RLC layer and has been assigned the RLC sequence number at the RLC layer, it can be discarded in 3GPP (3rd Generation Partnership Project).

3 P 17247 Among them. Currently, there are two schemes: one is not to discard, and the subsequent process is to be studied. For AM RLC, there is a scheme to set a discard timer for each RLC PDU. If the timer expires, it will discard if it does not receive the acknowledgement response from the receiver. Corresponding RLC SDU and update the send window. The second is to discard, and the subsequent process follows the "Send MRW" function of the WCDMA radio interface of the third generation mobile communication system. The disadvantage of the former is that it may cause buffer overload, and the packet delay budget ("DBB") is not clear for which proportion of SDUs can exceed the Quality of Service (QoS) requirements. The shortcomings of the latter are mainly manifested in two aspects: First, the SDU discard timer expires when a corresponding part of the RLC PDU has been sent successfully. The timeout may be caused by the scheduling delay, that is, the PDCP SDU is buffered at the PDCP layer. There are many detentions in the area. In these cases, it is unfair if the SDU is immediately discarded and the wireless resources are wasted. The second is the complexity of the "Send MRW" mechanism. In the existing scheme, there are two views on the flow of the RLC reset itself. As shown in FIG. 3, one way is to use the RLC reset mechanism of the WCDMA radio interface of the third generation mobile communication system, that is, the RESET PDU is used by the transmitting end in the RLC layer. The receiving end resets the other end. The other mode is that the RLC layer indicates its high-level radio resource control layer (RRC: Radio Resource Control) when the RLC reset trigger condition is satisfied, and the RLC entity corresponding to the receiving end is notified by the RRC layer signaling. The RLC reset function of the LTE radio interface is under discussion. The current conclusion is that the inter-base station handover will trigger the RLC reset. Other trigger conditions have not been discussed. Therefore, the definition of the trigger condition for reset is missing in the related art. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is a primary object of the present invention to provide a reset scheme for a radio link control entity that defines a trigger condition for reset. According to an embodiment of the present invention, a method of resetting a radio link control entity is provided. The method includes: setting a discard timer for each packet data convergence protocol service data unit, and starting a corresponding discard timer when the service data unit of the packet data aggregation protocol is delivered; the timeout period of the start discard timer expires If the service data unit corresponding to the started drop timer has been delivered to the radio link control entity and the radio link control sequence number has been assigned, the radio link control reset timer is started; In the case of timeout, if all the protocol data units involved in the service data unit are not successfully transmitted, the radio link control reset procedure is triggered.

4 P 17247 In the case that the started discard timer expires, the method further includes: if the service data unit corresponding to the started discard timer does not allocate the radio link control sequence number, discarding the service data unit. The method may further include: If the reset timer has not timed out, the drop timer of at least one of the service data units except the service data unit expires, and at least one service data unit has been assigned the radio link control sequence number In the case that if the reset timer of the earliest start of the reset timers of all the service data units triggers the reset process, all the reset timers that have been started are stopped. On the other hand, the method may further include: After the reset timer of one of the plurality of service data units is started, the reset timer of the other service data unit is not started, and before the start reset timer expires, the record is delivered to the wireless chain before the corresponding drop timer expires. Road control entity and allocation The service data unit of the line link serial number, and restarts the reset timer corresponding to the earliest start discard timer when the start reset timer is stopped. In addition, the startup reset timer does not time out. If the all the protocol data units involved in the corresponding service data unit are successfully sent, the restart timer is stopped. When the reset process is triggered, the method may include: the radio link control entity of the sending end controls the protocol data unit by resetting The radio link control entity of the receiving end is notified of the reset process, or the radio link control entity of the transmitting end instructs the upper layer to notify the radio link control entity of the receiving end to perform a reset process by signaling, wherein the upper layer is the radio resource control layer. In addition, the method may further include: stopping all the discard timers that have been started after the reset process is triggered; restarting the stopped discard timer after the reset process is completed, wherein, upon restarting, according to the following processing settings Restarted drop timer Duration: Keep the duration of all discard timers unchanged, or set the duration by the following predetermined rules: When stopping all discard timers that have been started, record the elapsed time of all discard timers. When restarting, use the original configuration duration. Subtracting the corresponding elapsed time, the obtained time value is taken as the duration of the corresponding discard timer. On the other hand, the method can further include: " After the reset process is triggered, all the discard timers that have been started are not stopped. . In addition, the duration of the reset timer is one or more automatic repeat request loopback times.

5 P 17247 In addition, in the method, a discard timer of each service data unit is set at a packet data convergence protocol layer. Moreover, the radio link control entity is an acknowledgment mode radio link control entity. By the above technical solution of the present invention, it is possible to prevent the SDU from staying in the buffer for too long, thereby causing the buffer to be over-loaded, and avoiding the SDU immediately discarding. The resulting wireless resources are wasted and unfair, while avoiding the complexity of using the "Send Mobile Receive Window (Send MRW)"mechanism; this scheme also has advantages over the scheme of setting a discard timer for each RLC PDU. The number of timers is reduced, the processing complexity and processing overhead are reduced. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute, The description is for the purpose of solving the present invention and does not constitute an undue limitation of the present invention. In the drawings: FIG. 1 is a "send mobile reception window (Send MRW)" in the third generation mobile communication system WCDMA according to the related art. Signaling flow chart; FIG. 2 is a signaling flow chart of the radio resource control entity reset in the third generation mobile communication system WCDMA of the related technology 3 is a signaling flowchart of a reset in a long term evolution system according to the related art; FIG. 4 is a flowchart of a method for resetting a radio link control entity according to an embodiment of the present invention; FIG. 5 is an AM of an embodiment of the present invention; FIG. 6a to FIG. 6c are flowcharts of the AM RLC entity reset processing according to the embodiment of the present invention; FIG. 7 is a flowchart of the SDU discard processing of the UM RLC or TM RLC according to an embodiment of the present invention; FIG. 8 is a flowchart of a process for resetting an AM RLC entity according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, a method for resetting a radio link control (RLC) entity is provided. The method is applicable to the (AM) RLC entity of the acknowledgment mode.

6 P 17247 As shown in FIG. 4, the reset method of the RLC entity according to this embodiment includes: Step S402: Set a discard timer for each Packet Data Convergence Protocol (PDCP) Service Data Unit (SDU), and deliver PDCP at the PDCP layer. When the SDU starts, the corresponding discard timer is started; Step S404, if the started discard timer expires, if the SDU corresponding to the started discard timer has been delivered to the RLC entity, and the RLC sequence number has been assigned, the device starts. The RLC resets the timer; Step S406: If the initiated reset timer expires, if all the PDCP protocol data units involved in the SDU are not successfully transmitted, the RLC reset process is triggered. If the initiated discard timer expires, the method further includes: if the SDU corresponding to the started discard timer does not allocate an RLC sequence number, discarding the SDU.

 In one aspect, the method can further include: in the case that the reset timer has not timed out,

If the discard timer of at least one SDU in the SDUs other than the SDU times out, and at least one SDU has been assigned the RLC sequence number, if the reset timer of the first start of each of the SDUs is triggered, the reset timer is triggered. During the reset process, all reset timers that have been started are stopped. In another aspect, the method may further include: after starting the reset timer of one of the plurality of SDUs for the first time, not resetting the reset timers of the other SDUs, and recording the corresponding discards before the started reset timer expires The SDU is delivered to the RLC entity before the timer expires and is assigned the SDU of the radio link sequence number, and in the case that the initiated reset timer is stopped, the reset timer corresponding to the earliest start discard timer is restarted. In addition, in the case that the initiated reset timer has not timed out, if all protocol data units involved in the corresponding SDU are successfully transmitted, the start reset timer is stopped. When the resetting process is triggered, the method may include: the RLC entity of the sending end notifies the RLC entity of the receiving end to perform a reset process by using the reset control protocol data unit, or the RLC entity of the sending end instructs the upper layer to notify the RLC entity of the receiving end to perform the reset process by signaling. , where the upper layer is the radio resource control layer. In addition, the method may further include: after triggering the reset process, stopping all the drop timers that have been started, and restarting all the drop timers that are stopped after the reset process is completed, wherein, upon restarting, Set the length of the restarted discard timer by the following processing: Keep the duration of all discard timers unchanged, or set the duration by the following predetermined rules: When stopping all discard timers that have been started, record the discard timers that have passed away. Time, in renew

P 17247 At startup, the corresponding elapsed time is subtracted from the original configuration duration, and the obtained time value is taken as the duration of the corresponding discard timer. On the other hand, it is also possible to not stop all the drop timers that have been started after the reset process is triggered. In addition, the duration of the reset timer is one or more automatic repeat request loopback times. In addition, in this method, a discard timer of each SDU is set at the PDCP layer. The invention will be described below in connection with specific examples. FIG. 5 shows an example of a specific processing flow of an AM RLC entity reset trigger. As shown in Figure 5, the specific processing is as follows: 51. The PDCP layer receives the PDCP SDU from the upper layer.

52. The PDCP layer sets and starts the SDU discard timer Timer_ Discard for each PDCP SDU.

53. The PDCP layer performs related processing: performing operations such as performing header compression, encryption, and submitting to the RLC layer for the PDCP SDU; 54. The RLC layer performs related processing, for example, receiving a PDCP SDU from the PDCP layer, performing segmentation, concatenation, and addition. Header information, submitting RLC PDUs to the underlying layer, receiving and processing status reports of the receiving terminal AM RLC entity, etc.;

55, Does Timer_Discard time out, if yes, go to 56; otherwise go to 51;

56, if it times out, it is determined whether the PDCP SDU has been submitted to the RLC layer and the RLC serial number is assigned, if yes, go to 57; otherwise, go to 58;

57, if yes, set and start the RLC reset timer Timer_RESET at the RLC layer, and go to 59;

58. If no, it indicates that the corresponding PDCP SDU has not been submitted to the RLC layer or has been submitted to the RLC layer but no RLC sequence number has been allocated in the RLC layer, then the corresponding PDCP SDU/PDU is discarded, and the process goes to 51;

8 P 17247 59, RLC reset timer Timer - RESET whether timeout (should be noted, may not have set RLC reset timer Timer - RESET), then go to 59-1; otherwise go to 59 - 2;

59 - 1 . If the determination is yes, if at least one of all RLC PDUs involved in the PDCP SDU is not successfully sent (for example, an acknowledgment response message is not received from the receiving AM RLC entity), the RLC reset process is triggered. Before the RLC reset, the PDCP layer can be notified to stop the SDU discard timer corresponding to all PDCP SDUs in the current buffer. After the RLC reset succeeds, the PDCP is notified to restart the PDCP SDU timer corresponding to all PDCP SDUs in the current buffer. To 51 ;

59 - 2, before the RLC reset timer Timer_RESET times out, if all the RLC PDUs involved in the PDCP SDU have been successfully sent (for example, all receive the acknowledgment response message of the receiving AM RLC entity), then stop the RLC reset timer Timer_RESET; before the RLC reset timer Timer-RESET timeout, if there is another PDCP SDU SDU drop timer Timer-Disard timeout, the corresponding PDCP SDU has not been submitted to the RLC layer or has Delivered to the RLC layer but performs PDCP SDU discard if the RLC layer has not yet assigned the RLC sequence number; if the corresponding PDCP SDU has been submitted to the RLC layer and the RLC sequence number has been assigned at the RLC layer, the new Timer_RESET timing is set respectively. If the earliest Timer-RESET timeout triggers the RLC reset process, then all other active Timer-RESET timers are stopped; or the new RLC reset timer Timer-RESET is not set, recording all the SDU Discard timings before the Timer_RESET timeout PDCP SD that has been submitted to the RLC layer and has been assigned the RLC serial number at the RLC layer when it times out U, restarts the Timer_RESET timer corresponding to the earliest SDU Discard timer when it is stopped before Timer_RESET times out, and then goes to 51. In the process shown in FIG. 5, it should be noted that during the actual execution, the Timer-Discred and the Timer_RESET are operated in an interrupt mode, and may occur at any time. In addition, the present embodiment does not involve other processes of the PDCP layer and the RLC layer. The complicated processing, so the actual occurrence may be different from this embodiment. Fig. 6a to Fig. 6c show an example 2 of the processing flow of the AM RLC reset. Figure 6a shows the main flow chart. As shown in Figure 6a, the specific steps are as follows:

61a, the PDCP layer receives the PDCP SDU from the upper layer;

9 P17247 62a, the PDCP layer sets and starts the SDU discard timer Timer_Discard for each PDCP SDU;

63a, the PDCP layer performs related processing: performing operations such as performing header compression, encryption, and submitting to the RLC layer for the PDCP SDU; 64a, the RLC layer performs related processing: for example, receiving the PDCP SDU from the PDCP layer, performing segmentation, concatenation, and addition Header information, submitting RLC PDUs to the underlying layer, receiving and processing status reports of the receiving terminal AM RLC entity, etc.; During the execution of the main program, if the SDU discards the timer Timer-Disard timeout, the corresponding Timer_Discard interrupt routine is triggered after the stack saves the breakpoint related information, and the main program continues to execute the rest of the flow; if the RLC reset timer Timer_RESET times out, After the stack saves the breakpoint related information, the corresponding Timer-RESET interrupt service routine is triggered, and the main program continues to execute the remaining processes. Figure 6b is a flow chart of the SDU drop timer Timer_Discard interrupt service routine. When the Timer_Discard timer expires, the process shown in Figure 6b is triggered. The specific steps are as follows: 61b, whether the PDCP SDU has been submitted to the RLC layer and the RLC serial number is assigned, if yes, go to 62b; otherwise, go to 63b;

62b, Yes, then set and start the RLC reset timer at the RLC layer Timer - RESET, turn

61b;

63b, No, indicating that the corresponding PDCP SDU has not been submitted to the RLC layer or has been submitted to the RLC layer but has not been assigned an RLC sequence number at the RLC layer, then the corresponding PDCP SDU/PDU is discarded, and 64b is transferred;

64b, before the RLC reset timer Timer_RESET times out, if all the RLC PDUs involved in the PDCP SDU are successfully sent (for example, the acknowledgment response message of the receiving end AM RLC entity is received), the RLC reset timer Timer_RESET is stopped. Before the RLC reset timer Timer_RESET times out, if there is another PDCP SDU SDU drop timer Timer-Disard timeout, the corresponding PDCP SDU has not been submitted to the RLC layer or has been submitted to the RLC layer but at the RLC layer. Perform PDCP SDU discard if no RLC sequence number has been assigned; if the corresponding PDCP SDU has been submitted to the RLC layer and the RLC sequence number has been assigned at the RLC layer, set the new Timer-RESET timer separately, if the earliest

10 P 17247 Timer_RESET timeout triggers the RLC reset process, then stops all other active Timer-RESET timers; or does not set a new RLC reset timer Timer-RESET, records the Timer-RESET timeout before all the SDU Discard timers have timed out The PDCP SDU that has been assigned the RLC sequence number to the RLC layer and has been allocated the RLC sequence number at the RLC layer, restarts the Timer_RESET timer corresponding to the earliest SDU Discard timer when the timer expires, and so on; i' J 61b; Among them, it should be noted that after the execution of the interrupt service program is completed, the breakpoint is returned according to the relevant information saved in the stack. Figure 6c is a flow chart of the RLC reset timer Timer_RESET interrupt service routine. When the Timer_RESET timer expires, the flow shown in Figure 6c is triggered. The specific steps are as follows:

61c. If at least one of all RLC PDUs involved in the PDCP SDU is not successfully sent (for example, no acknowledgement response message is received from the receiving AM RLC entity), the RLC reset process is triggered; go to 61c. Similarly, after the execution of the interrupt service routine is completed, it returns to the breakpoint according to the relevant information saved in the stack. Figure 7 shows the UM RLC or TM RLC SDU discarding process, the specific steps are as follows: 71, the PDCP layer receives the PDCP SDU from the upper layer;

72. The PDCP layer sets and starts the SDU discard timer for each PDCP SDU. Timer-discrete; 73. The PDCP layer performs related processing: performing header compression, encryption, and direction on the PDCP SDU.

RLC layer submission and other operations;

74. The RLC layer performs related processing: for example, receiving a PDCP SDU from the PDCP layer, performing segmentation, concatenation, adding header information, submitting an RLC PDU to the bottom layer, receiving and processing a status report of the receiving terminal AM RLC entity, and the like; Determine if Timer_Discard times out? Yes, go to 76; otherwise go to 71;

11 P 17247 76. In case of timeout, discard the relevant PDCP SDU/PDU and go to 71. That is, PDCP SDU/PDU discarding is performed regardless of whether the PDCP SDU has been submitted to the RLC layer and the RLC sequence number is assigned. Figure 8 shows the AM RLC entity reset triggering process, the specific steps are as follows: 81, the PDCP layer receives the PDCP SDU from the upper layer;

82. The PDCP layer sets and starts the SDU discard timer Timer_ Discard for each PDCP SDU.

83. The PDCP layer performs related processing: performing operations such as performing header compression, encryption, and delivery to the RLC layer on the PDCP SDU. 84. The RLC layer performs related processing: for example, receiving a PDCP SDU from the PDCP layer, performing segmentation, concatenation, and addition. Header information, submitting RLC PDUs to the underlying layer, receiving and processing status reports of the receiving terminal AM RLC entity, etc.;

85, judge whether Timer-Discred timed out, then go to 86; otherwise go to 81;

86. In the case of timeout, whether the PDCP SDU has been submitted to the RLC layer and the RLC serial number is assigned, if yes, go to 87; otherwise, go to 88;

87, trigger the RLC reset process, go to 81;

88. Discard the corresponding PDCP SDU/PDU, and go to 81. In summary, the present invention discloses the RLC reset trigger condition, which avoids the SDU being stuck in the buffer for too long and causing the buffer to be overloaded. It avoids the waste of wireless resources and unfairness caused by SDU immediate discarding, and avoids the complexity of adopting the "Send MRW" mechanism; this scheme sets a discard timer with each RLC PDU. Compared to the advantages, the number of timers required is much lower, which reduces processing complexity and processing overhead. The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

12 P 17247

Claims

 A method for resetting a radio link control entity, characterized in that it comprises:  For each packet data convergence protocol service data unit, a drop timer is separately set, and a corresponding drop timer is started when the service data unit is delivered by a high layer of the packet data convergence protocol layer;  In case the started discard timer expires, if the service data unit corresponding to the initiated discard timer has been delivered to the radio link control entity and has been assigned a radio link control sequence number, then Initiating a radio link control reset timer;  In the event that the initiated reset timer expires, if all of the radio link control protocol data units involved in the service data unit are not successfully transmitted, the radio link control reset procedure is triggered. The method according to claim 1, wherein in the case that the discarded discard timer expires, the method further includes:  If the service data unit corresponding to the initiated discard timer does not allocate the radio link control sequence number, the service data unit is discarded. The method according to claim 1, further comprising:  If the reset timer has not timed out, the discard timer of at least one of the service data units except the service data unit expires, and the at least one service data unit has been allocated In the case of the radio link control sequence number, if the reset timer that is the earliest start of the reset timer of each of the service data units triggers the reset process, all the reset timers that have been started are stopped. The method according to claim 1, further comprising:  After the reset timer of one of the plurality of service data units is started for the first time, the reset timer of the other service data unit is not started, and the corresponding drop timer is recorded before the started reset timer expires. Retrieving the service data unit of the radio link control entity and assigning the radio link sequence number before the timeout, and restarting the earliest start discard timer corresponding to the restart timer being stopped Reset the timer. 13 P17247 The method according to claim 1, wherein, if the restart timer that is started does not time out, if all the protocol data units involved in the corresponding service data unit are successfully sent, the startup is stopped. The reset timer. The method according to claim 1, wherein when the resetting process is triggered, the method includes:  The radio link control entity of the transmitting end notifies the radio link control entity of the receiving end to perform the reset process by using a reset control protocol data unit, or the radio link control entity of the transmitting end instructs its upper layer to notify the receiving end by signaling The radio link control entity performs the reset process, where the upper layer is a radio resource control layer. The method according to claim 1, further comprising:  After the reset process is triggered, all the drop timers that have been started are stopped, and all the drop timers that are stopped are restarted after the reset process is completed, wherein, upon restarting, the restart is performed by the following processing settings. Duration of the drop timer:  Keeping the duration of all the discarding timers unchanged, or setting the duration by the following predetermined rule: when stopping all the discarding timers that have been started, recording the elapsed time of each of the discarding timers, when restarting, The corresponding elapsed time is subtracted from the original configuration duration, and the obtained time value is taken as the duration of the corresponding discard timer. 8. The method according to claim 1, further comprising:  After the reset process is triggered, all drop timers that have been started are not stopped. The method according to any one of claims 1 to 8, wherein the duration of the reset timer is one or more automatic repeat request loopback times. The method according to any one of claims 1 to 8, characterized in that the discarding timer of each of the service data units is set at a packet data convergence protocol layer. The method according to any one of claims 1 to 8, wherein the radio link control entity is an acknowledge mode radio link control entity. 14 P 17247